Fig. 2

a Using LEA can significantly shorten the duration between cervical dilation of 2 cm and delivery compared to non-LEA-2 group (P < 0.001) and prolong the duration of the women with with cervical dilation more than 4 cm compared to non-LEA-4 group (P = 0.043), while there was no significant difference between non-LEA-3 group and LEA-3 group (P = 0.767). b Using LEA can obviously prolong the duration of first-second stage in the women with 2 cm cervical dilation (P < 0.001) and 3 cm cervical dilation (P = 0.014), while there was no significant difference in the two groups with cervical dilation more than 4 cm (P = 0.69). c This picture shows that the timing of epidural placement at 3 cm cervical dilation is a turning point. d Once the cervical dilation is more than 2 cm, no matter when is the LEA applied, the postpartum blood loss of LEA group is more than the non-LEA group.